Antenna arrays, in particular for base stations for mobile radio communications devices, generally have a vertically aligned reflector arrangement in which two or more antenna element devices are provided, and are arranged offset one above the other in the vertical direction. These may be single-polarized antenna element arrangements or, in general, dual-polarized antenna element arrangements which transmit and receive with polarizations which are offset through 90° with respect to one another.
Furthermore, these may be antenna arrangements which receive beams in only one frequency band or in two or more frequency bands, for which purpose antenna element arrangements are then provided which are matched to the appropriate frequency bands. To this extent, reference is made by way of example to the previously published antenna arrangements according to DE 198 23 749 A1.
In the case of antenna arrangements, especially for mobile radio communications technology, it is in some cases also desirable to be able to set or preselect a specific beam angle. For example, phase shift arrangements such as those which are known from WO 01/13459 A1 may be used to vary the so-called down-tilt angle. Adjustment of the phase shift element results in a delay time change and hence in a phase shift, so that it is possible to adjust the down-tilt angle.
However, as mentioned, there are also situations in which, for example, a pair of antenna element arrangements which are arranged one above the other should in each case be operated at a down-tilt angle which, although it can be preselected, is then preset in a fixed manner. It is also possible, for example by means of the phase shift arrangement which is already known from the cited WO 01/13459 A1, to feed not only in each case one individual antenna element to be fed but, for example, a pair of antenna elements which are arranged adjacent and vertically one above the other. In such a case, this pair of antenna elements are then preferably operated with a fixed preset phase angle relative to one another and thus with a fixed defined down-tilt angle which acts relatively between these two antenna elements. If, by way of example, a pair of antenna elements such as these are also driven with different phase angles via the phase shifters which have been mentioned, then it is possible to set a greater or lesser down-tilt angle, although a relative phase offset and hence a relative different down-tilt angle will then always remain as a permanent preset. This can be achieved by designing the coaxial cable which leads to one antenna element of the pair of antenna elements to be somewhat longer than the coaxial cable which leads to the second antenna element in the pair of antenna elements, so that the change in the delay time produces the desired relative phase offset.
Furthermore, a pair of antenna element arrangements such as these which can be fed with different phase angles can be connected using a stripline technique.
A certain amount of transformation is also frequently carried out in this case, and this means that an impedance conversion device is often or typically required. This impedance conversion device may likewise once again be provided by means of stripline technology or by using boards or coaxial cable solutions. If a coaxial cable is used as a feed, then any desired impedance conversion can be achieved, for example, by using two coaxial cable sections with different internal conductor diameters, connected in series.
In one comparatively simple antenna arrangement using stamped dipole antenna elements, electrical power splitting between antenna elements which are arranged offset with respect to one another in front of a reflector plate, for example in the form of dipole antenna elements, can also be achieved via an elongated stamped transmission line which has an intermediate line section which, for example, has a narrower width. This allows the transformation and impedance conversion to be carried out. By preselecting the feed point for an inner conductor cable which is to be connected (e.g., soldered coaxial cable), it is then possible to set the phase shift, which can be preselected, for the two antenna element arrangements, and hence a down-tilt angle which can be preselected, in a fixed and permanent manner. One implementation as described above has been disclosed for example, in EP 0 826 250 B1.
The illustrative non-limiting technology described herein provides an improved feed and connecting device for at least in each case one pair of antenna element devices which are arranged offset with respect to one another, which feed and connecting device can be used for widely differing types of antennas and which at the same time is intended to be as insensitive as possible to external influences, for example interference fields.
An exemplary illustrative non-limiting connecting device allows a direct connection to in each case one pair of antenna element devices which are arranged offset with respect to one another, to be precise in a low-cost implementation. In such a case, two antenna elements, for example in the form of two dipole arrangements, are connected taking into account impedance matching, power matching and/or phase matching. The electrical characteristics are preferably, in one exemplary illustrative non-limiting arrangement, achieved only by varying the outer conductor (in particular by varying a cross section) and/or only by varying the dielectric (in particular by varying the cross section). This makes it possible to use an inner conductor without any sudden diameter changes, and this has been found to be particularly cost-effective. The exemplary illustrative non-limiting connecting device may also be used irrespective of the reflector or reflector type being used. Advantages are also obtained in particular if the solution is designed using a casting technique. This also contributes to a cost-effective solution. In particular, the exemplary illustrative non-limiting connecting module is insensitive to external influences, in particular such as interference fields and can be used irrespective of the reflector type. In the process, a direct connection is created to the respective antenna element, in particular dipole antenna element.
One illustrative non-limiting particularly advantageous arrangement provides a connecting device implementation that is in integral form, to be precise with an outer conductor housing which in the end can be handled integrally and has an integrated inner conductor. In particular, this also avoids intermodulation problems, such as those which occur frequently in the prior art in a disadvantageous manner that is difficult to deal with.
In one exemplary illustrative non-limiting implementation, the entire outer conductor arrangement is produced using casting technology, with the inner conductor being produced by insertion of an inner conductor or inner conductor wire that preferably has no sudden changes in diameter. The inserted inner conductor is electrically conductively isolated from the outer conductor arrangement by the use of appropriate plastic holders, that is to say, in general nonconductive elements.
The coaxial cable feed can be connected at a connection point which is preferably provided in the central area of the connecting device.
The exemplary illustrative non-limiting arrangement may preferably also be in the form of a double arrangement, preferably being symmetrical with respect to a vertical plane of symmetry running in the longitudinal direction, to be precise with two connections points which are preferably arranged centrally opposite one another, preferably for two coaxial cables. This makes it possible to provide a feed to two pairs of antenna element arrangements which, for example, act as a dual-polarized antenna element arrangement, thus having an appropriate feed via a separate inner conductor for each of the two polarizations. The outer conductor arrangement is provided for both inner conductors, with the two inner conductors preferably being screened from one another by means of a longitudinally running vertical web which is electrically connected to the outer conductor arrangement.
In one exemplary illustrative non-limiting implementation, the connecting device is in the form of a component which can be handled on its own and can be inserted, and fitted to a reflector, as required. In one alternative exemplary implementation, the outer conductor arrangement may, however, also be produced as an integral functional part, in the factory, as part of the reflector arrangement, preferably on the side of the reflector facing away from the antenna element arrangement. With an implementation such as this, all that is necessary is to insert an inner conductor arrangement into the outer conductor arrangement of the connecting device, which forms a functional part of the reflector, with the functional part that is formed in this way being closed by fitting a cover arrangement.
Since, in the exemplary illustrative non-limiting solution, both the inner conductor and the outer conductor housing are, in the end, integral and can be handled integrally no intermodulation problems occur either, as is of major importance especially for mobile radio communications technology.